Wide field-of-view virtual image projector

Abstract

A wide field-of-view virtual image projector includes a rod light guide that is embossed with at least a first diffraction grating and a second diffraction grating that is substantially parallel to the first diffraction grating. The first diffraction grating is configured to receive a first light ray, and to project first diffracted light rays from the rod light guide at a first range of angles. The second diffraction grating is configured to receive a second light ray, and to project second diffracted light rays from the rod light guide at a second range of angles. The virtual image projector further includes a slab light guide configured to receive the first diffracted light rays and the second diffracted light rays, and to diffract the first diffracted light rays and the second diffracted light rays out of the slab light guide to generate a virtual image with a wide field-of view.

What is claimed is: 
     
       1. A method comprising:
 receiving data corresponding to a virtual image; 
 controlling an illuminator to inject first light rays into a first diffraction grating of a rod light guide effective to diffract the first light rays out of the rod light guide at a first range of angles and into a slab light guide; and 
 controlling the illuminator to inject second light rays into a second diffraction grating of the rod light guide effective to diffract the second light rays out of the rod light guide at a second range of angles and into the slab light guide, the first diffraction grating substantially parallel to the second diffraction grating on a first surface of the rod light guide, the first diffraction grating having a first spatial frequency that is different than a second spatial frequency of the second diffraction grating, the first spatial frequency causing the first diffraction grating to project the first diffracted light rays at the first range of angles, and the second spatial frequency causing the second diffraction grating to project the second diffracted light rays at the second range of angles, and the slab light guide configured to generate the virtual image. 
 
     
     
       2. The method as described in  claim 1 , wherein the slab light guide is configured to generate the virtual image with a field-of-view that is equal to the sum of the first range of angles and the second range of angles. 
     
     
       3. The method as described in  claim 1 , wherein the first range of angles is different than the second range of angles. 
     
     
       4. The method as described in  claim 1 , further comprising:
 controlling the illuminator to inject third light rays into a third diffraction grating of the rod light guide effective to diffract the third light rays out of the rod light guide at a third range of angles and into the slab light guide. 
 
     
     
       5. The method as described in  claim 4 , further comprising:
 controlling the illuminator to inject fourth light rays into a fourth diffraction grating of the rod light guide effective to diffract the fourth light rays out of the rod light guide at a fourth range of angles and into the slab light guide. 
 
     
     
       6. The method as described in  claim 5 , wherein the slab light guide generates the virtual image with a field-of-view that is equal to the sum of the first range of angles, the second range of angles, the third range of angles, and the fourth range of angles. 
     
     
       7. The method as described in  claim 5 , wherein: the first range of angles is approximately −60 degrees to −30 degrees, the second range of angles is approximately −30 degrees to 0 degrees, the third range of angles is approximately 0 degrees to 30 degrees, the fourth range of angles is approximately 30 degrees to 60 degrees. 
     
     
       8. The method as described in  claim 1 , wherein the slab light guide is configured to generate the virtual image with a field-of-view that is approximately 120 degrees. 
     
     
       9. The method as described in  claim 1 , wherein the slab light guide is embossed with a third diffraction grating that is substantially perpendicular to the first diffraction grating and the second diffraction grating, the third diffraction grating configured to cause the first diffracted light rays and the second diffracted light rays to be projected out of the slab light guide to generate the virtual image. 
     
     
       10. The method as described in  claim 1 , wherein the slab light guide is configured with a partially-reflecting mirror that is configured to reflect a portion, and transmit another portion, of each of the first diffracted light rays and the second diffracted light rays. 
     
     
       11. One or more computer-readable storage media comprising instructions stored thereon that, responsive to execution by one or more processors, perform operations comprising:
 receiving data corresponding to a virtual image; 
 controlling an illuminator to inject first light rays into a first diffraction grating of a rod light guide effective to diffract the first light rays out of the rod light guide at a first range of angles and into a slab light guide; 
 controlling the illuminator to inject second light rays into a second diffraction grating of the rod light guide effective to diffract the second light rays out of the rod light guide at a second range of angles and into the slab light guide, the first diffraction grating substantially parallel to the second diffraction grating on a first surface of the rod light guide, the first diffraction grating having a first spatial frequency that is different than a second spatial frequency of the second diffraction grating, the first spatial frequency causing the first diffraction grating to project the first diffracted light rays at the first range of angles, and the second spatial frequency causing the second diffraction grating to project the second diffracted light rays at the second range of angles, and the slab light guide configured to generate the virtual image. 
 
     
     
       12. The one or more computer-readable storage media of  claim 11 , wherein the slab light guide is configured to generate the virtual image with a field-of-view that is equal to the sum of the first range of angles and the second range of angles. 
     
     
       13. The one or more computer-readable storage media of  claim 11 , wherein the first range of angles is different than the second range of angles. 
     
     
       14. The one or more computer-readable storage media of  claim 11 , wherein the operations further comprise controlling the illuminator to inject third light rays into a third diffraction grating of the rod light guide effective to diffract the third light rays out of the rod light guide at a third range of angles and into the slab light guide. 
     
     
       15. The one or more computer-readable storage media of  claim 14 , wherein the operations further comprise controlling the illuminator to inject fourth light rays into a fourth diffraction grating of the rod light guide effective to diffract the fourth light rays out of the rod light guide at a fourth range of angles and into the slab light guide. 
     
     
       16. The one or more computer-readable storage media of  claim 15 , wherein the slab light guide generates the virtual image with a field-of-view that is equal to the sum of the first range of angles, the second range of angles, the third range of angles, and the fourth range of angles. 
     
     
       17. The one or more computer-readable storage media of  claim 15 , wherein: the first range of angles is approximately −60 degrees to −30 degrees, the second range of angles is approximately −30 degrees to 0 degrees, the third range of angles is approximately 0 degrees to 30 degrees, the fourth range of angles is approximately 30 degrees to 60 degrees. 
     
     
       18. The one or more computer-readable storage media of  claim 11 , wherein the slab light guide is embossed with a third diffraction grating that is substantially perpendicular to the first diffraction grating and the second diffraction grating, the third diffraction grating configured to cause the first diffracted light rays and the second diffracted light rays to be projected out of the slab light guide to generate the virtual image. 
     
     
       19. The one or more computer-readable storage media of  claim 11 , wherein the slab light guide is configured to generate the virtual image with a field-of-view that is approximately 120 degrees. 
     
     
       20. The one or more computer-readable storage media of  claim 11 , wherein the slab light guide is configured with a partially-reflecting mirror that is configured to reflect a portion, and transmit another portion, of each of the first diffracted light rays and the second diffracted light rays.